Showing papers on "Benzoic acid published in 2006"
TL;DR: This method would be a useful method for the preparation of various functionalized aryl- and alkenyl-carboxylic acids.
Abstract: When the esters of arylboronic acids with 2,2-dimethylpropan-1,3-diol were treated with a catalytic amount of [Rh(OH)(cod)]2 in the presence of 1,3-bis(diphenylphosphino)propane and CsF in dioxane at 60 °C under carbon dioxide atmosphere, the benzoic acid derivatives were obtained in good yields. Reactions of alkenylboronic esters also proceeded under similar conditions to give α,β-unsaturated carboxylic acids. As these boronic esters are now easily available through coupling or direct borylation reactions, this method would be a useful method for the preparation of various functionalized aryl- and alkenyl-carboxylic acids.
268 citations
TL;DR: Interestingly, propranolol derivatives, good substrates for hCE-2, were easily hydrolyzed by substitution of the methyl group on the 2-position of the acyl moiety, but were barely Hydrolyzed when the methyl Group was substituted on the 3-position, suggesting that hCE -2 does not easily form acylated intermediates because of conformational interference in its active site.
Abstract: Hydrolase activity from human liver and small intestine microsomes was compared with that of recombinant human carboxylesterases, hCE-1 and hCE-2. Although both hCE-1 and hCE-2 are present in human liver, the dominant component was found to be hCE-1, whereas the hydrolase activity of the human small intestine was found to be predominantly hCE-2. hCE-2 has a limited ability to hydrolyze large acyl compound substrates. Interestingly, propranolol derivatives, good substrates for hCE-2, were easily hydrolyzed by substitution of the methyl group on the 2-position of the acyl moiety, but were barely hydrolyzed when the methyl group was substituted on the 3-position. These findings suggest that hCE-2 does not easily form acylated intermediates because of conformational interference in its active site. In contrast, hCE-1 could hydrolyze a variety of substrates. The hydrolytic activity of hCE-2 increased with increasing alcohol chain length in benzoic acid derivative substrates, whereas hCE-1 preferentially catalyzed the hydrolysis of substrates with short alcohol chains. Kinetic data showed that the determining factor for the rate of hydrolysis of p-aminobenzoic acid esters was V(max) for hCE-1 and K(m) for hCE-2. Furthermore, the addition of hydrophobic alcohols to the reaction mixture with p-aminobenzoic acid propyl ester induced high and low levels of transesterification by hCE-1 and hCE-2, respectively. When considering the substrate specificities of hCE-1, it is necessary to consider the transesterification ability of hCE-1, in addition to the binding structure of the substrate in the active site of the enzyme.
227 citations
TL;DR: A modified sol−gel method was employed to synthesize metal-doped TiO2 with varied dopant concentrations using titanium butoxide and metal nitrate hydrate as the precursors and hydrothermal posttreatment as discussed by the authors.
Abstract: A modified sol−gel method was employed to synthesize metal-doped TiO2 with varied dopant concentrations using titanium butoxide and metal nitrate hydrate as the precursors and hydrothermal posttreatment. The prepared samples were characterized by XRD, XPS, TEM, BET, UV−vis/diffuse reflectance, PZC measurement, Raman spectroscopy, photoluminescence, and fluorescence lifetime, while the photocatalytic activities were tested using benzoic acid as the model compound. Ga-doped TiO2 exhibits the highest photoactivity among the prepared metal-doped TiO2 photocatalysts. This is most likely due to the good dispersion of Ga dopant onto the surface of TiO2, adequate surface area, and decrease of recombination center on the surface of Ga-doped TiO2 photocatalyst. The optimum dopant concentration was found to be 0.1 wt % for Ga-doped TiO2.
183 citations
TL;DR: In this paper, a new static apparatus, capable of measuring vapor pressures in the range (0.4 to 133) Pa and in the temperature range (243 to 413) K, is fully described.
Abstract: A new static apparatus, capable of measuring vapor pressures in the range (0.4 to 133) Pa and in the temperature range (243 to 413) K, is fully described. The performance of the new apparatus was checked by measuring the vapor pressures of four compounds recommended as reference materials for the measurement of vapor pressurenaphthalene, benzoic acid, benzophenone, and ferrocene. A recommended value for the enthalpy of sublimation of benzophenone, (298.15 K) = (95.1 ± 1.9) kJ·mol-1, is suggested.
154 citations
TL;DR: In this article, the process of molecular self-assembly has been studied in concentrated solutions using FTIR spectroscopy, and three carboxylic acids, benzoic, tetrolic, and mandelic acids, have been chosen on the basis of their differing crystal chemistries, as reflected in observed hydrogen-bonding motifs.
Abstract: Little is known concerning the precise molecular pathway that links fluid-phase molecules to those in nascent crystal nuclei. In this paper the process of molecular self-assembly has been studied in concentrated solutions using FTIR spectroscopy. Three carboxylic acids, benzoic, tetrolic, and mandelic acids, have been chosen on the basis of their differing crystal chemistries, as reflected in observed hydrogen-bonding motifs. Using the solid-state spectra as a means of unambiguous assignment of carboxyl and hydroxyl vibrations associated with hydrogen bonding, spectroscopic data are reported for solutions as a function of both composition and solvent. In the cases of benzoic acid and tetrolic acid, a link between the growth synthon and the structural synthon is apparent. Mandelic acid, on the other hand, provides a more complex case in which strong solvation effects are evident, leading to the conclusion that significant molecular rearrangement must occur within the developing crystal nuclei.
136 citations
TL;DR: In this article, the major odor-active compounds of fermented soy sauce were acetic acid, furfuryl alcohol, 2methoxyphenol, benzeneethanol, benzoic acid, butyric acid, 2-ethyl-4-hydroxy-5-methyl-3(2H) furanone, and 2-methylbutanal.
Abstract: Volatile compounds in fermented and acid-hydrolyzed soy sauces were isolated and analyzed using solvent extraction and solid-phase microextraction. Quantitatively, alcohols and esters were dominant in the volatiles of fermented soy sauce, whereas heterocyclic compounds, including pyrazines and furans, and acids were relatively abundant in the acid-hydrolyzed soy sauce. The odor-active compounds were also evaluated. The major odor-active compounds of fermented soy sauce were acetic acid, furfuryl alcohol, 2-methoxyphenol, benzeneethanol, benzoic acid, butyric acid, 2-ethyl-4-hydroxy-5-methyl-3(2H) furanone, and 2-methylbutanal, whereas acetic acid, 2-methoxyphenol, formic acid, benzoic acid, 2,5-dimethylpyrazine, 2,6-dimethylpyrazine, butyric acid, 2,6-dimethoxyphenol, 3-hydroxy-2-methyl-4H-pyran-4-one, 2-acetyl-5-methylfuran, 2,5-dimethyl-3-ethylpyrazine, and 2-methylbutanal constituted the major odor-active compounds of acid-hydrolyzed soy sauce.
135 citations
TL;DR: In this paper, the photocatalytic degradation of formic acid (FA) and benzoic acid was investigated in TiO2 and ZnO water suspensions under different experimental conditions, and the effect of different initial amounts of substrates and the dependence of the reaction rate on the initial pH of the TiO 2 suspensions was interpreted under the light of a pseudosteady state Langmuir-Hinshelwood rate form and of the electrostatic interactions occurring at the water-semiconductor interface.
Abstract: The photocatalytic degradation of formic acid (FA) and benzoic acid (BA), chosen as model organic molecules with acidic properties, was investigated in TiO2 and ZnO water suspensions under different experimental conditions. Hydrogen peroxide evolution, formed through a reductive pathway started by conduction band electrons, was also simultaneously monitored during the degradation runs. The effect of different initial amounts of substrates and the dependence of the reaction rate on the initial pH of the TiO2 suspensions was interpreted under the light of a pseudo-steady state Langmuir–Hinshelwood rate form and of the electrostatic interactions occurring at the water–semiconductor interface. ZnO appeared a more effective photocatalyst than TiO2 for BA, but not for FA degradation. A much higher amount of hydrogen peroxide was detected in ZnO irradiated suspensions, both in the presence and in the absence of the substrates, mainly because of its lower photocatalytic decomposition rate on such oxide. The rate of hydrogen peroxide evolution during the photocatalytic oxidation of BA on TiO2 could be related to the rate of the oxidation process, while H2O2 could not be detected during the photocatalytic degradation of FA on this oxide, mainly because of the reduced shielding ability of this substrate.
126 citations
TL;DR: It is suggested that benzoic acid exerts strong antimicrobial effects in the gastrointestinal tract of piglets and therefore enhances growth performance and nitrogen retention.
Abstract: In order to investigate the effects of benzoic acid on growth performance, nutrient digestibility, nitrogen balance and gastrointestinal microflora of piglets, we conducted a performance experiment and a separate balance study. The performance experiment involved four different dietary treatments: (1) basal diet (negative control); (2) basal diet supplemented with benzoic acid at 5 g/kg; (3) basal diet supplemented with benzoic acid at 10 g/kg; (4) basal diet supplemented with potassium diformate at 12 g/kg. Each dietary treatment was assigned to nine replicate groups, each consisting of two piglets. Live weight, daily weight gain, feed intake and feed conversion ratio were monitored as performance parameters over a 35-day period. Supplementation of the diet with benzoic acid resulted in a dose-dependent increase in feed intake and body weight gain and an improved feed conversion ratio. Piglets fed the diet supplemented with benzoic acid at 10 g/kg outperformed the control piglets in mean feed intake, body weight gain and feed conversion ratio by 9%, 15% and 6% respectively. Growth performance of the piglets fed the diet with benzoic acid at 10 g/kg was similar to that of piglets fed the diet supplemented with potassium diformate. In the balance experiment three groups of six piglets each were fed either a control diet or diets supplemented with benzoic acid at 5 or 10 g/kg respectively. Benzoic acid did not significantly affect nutrient digestibility but increased nitrogen retention. Piglets fed the diets supplemented with benzoic acid at 5 or 10 g/kg retained 5% and 6% more nitrogen, respectively, than control piglets. Supplementation of benzoic acid did not influence the pH value or the concentration of ammonia in the gastrointestinal tract but reduced the number of bacteria in the digesta. In the stomach the number of total aerobic, total anaerobic, lactic acid forming and gram-negative bacteria was reduced; in the duodenum the presence of benzoic acid reduced the number of gram-negative bacteria and in the ileum the number of total aerobic bacteria in a dose-dependent manner. Benzoic acid also considerably reduced the concentration of acetic acid in the duodenum. In conclusion, the data of this study suggest that benzoic acid exerts strong antimicrobial effects in the gastrointestinal tract of piglets and therefore enhances growth performance and nitrogen retention.
125 citations
TL;DR: In this article, some Bronsted acidic ionic liquids (TSILs) that bear an alkane sulfonic acid group in an acyclic trialkanylammonium cation were synthesized and their uses as dual solvent−catalysts for Fischer esterification reactions of acetic acid, metacetonic acid, and benzoic acid with ethanol, butanol, and benzyl alcohol were investigated.
Abstract: Some novel Bronsted acidic ionic liquids (TSILs) that bear an alkane sulfonic acid group in an acyclic trialkanylammonium cation were synthesized and their uses as dual solvent−catalysts for Fischer esterification reactions of acetic acid, metacetonic acid, and benzoic acid with ethanol, butanol, and benzyl alcohol were investigated. The reactions were completed smoothly at room temperature to 110 °C for 1.5−3.0 h with good yields of 88−95%. The results indicate that catalytic activity depends on anion acidity and the solubility of the starting material in TSILs. The increasing of the anion's acidity improves the catalytic activity of the TSILs. Furthermore, the produced esters could be separated by decantation after the reaction and the TSILs could be reused without noticeably decreasing the catalytic activity.
116 citations
TL;DR: In this article, the authors used thermochemolysis coupled with gas chromatography and mass spectrometry to determine the structure of humic acids (HA) extracted from a sewage sludge and straw mixture at different steps of composting.
110 citations
TL;DR: A simple method for the direct Ortho-arylation of benzoic acid amides has been developed and presents an alternative to the currently used ortho-lithiation strategies for the synthesis of arylated benzoIC acid derivatives.
TL;DR: The first-order rate law was found to be applicable for the kinetic data of adsorption and the observed orders were explained in terms of electrostatic, dispersion and hydrogen bonding interactions between the surface and the adsorbate species.
TL;DR: The enantioselective direct aldol reaction, organocatalyzed by recoverable BINAM-prolinamide derivatives can be highly accelerated by a catalytic amount of a carboxylic acid without a detrimental of the obtained enanti-oselectivities as discussed by the authors.
Abstract: The enantioselective direct aldol reaction, organocatalyzed by recoverable BINAM-prolinamide derivatives can be highly accelerated by a catalytic amount of a carboxylic acid without a detrimental of the obtained enantioselectivities. From the study of suitable acids and reaction conditions, benzoic acid in aqueous DMF or in water was shown to give the best results with high yields and enantioselectivities. Thus, the reaction between p -nitrobenzaldehyde and acetone catalyzed by ( S a )-BINAM- l -Pro and benzoic acid can be carried out at −20 °C in only 8.5 h to give the expected product with 86% ee. In the case of butan-2-one, the iso - and the anti -isomers are obtained in a 1:1 isomer ratio up to 99% ee. Cyclohexanone gives the anti -aldol in up to 99% dr and 97% ee in only 2 h. The opposite diastereoselectivity is obtained in the case of cyclopentanone with lower ee up to 65% for the syn and 85% for the anti -isomer.
TL;DR: The Schiff base (H2fsal-ohyba) derived from 3-formylsalicylic acid and o-hydroxybenzylamine has been covalently bonded to chloromethylated polystyrene cross-linked with 5% divinylbenzeneCross-linked complexes have been characterised by various techniques and their catalytic activities have been compared.
Abstract: The Schiff base (H2fsal-ohyba) derived from 3-formylsalicylic acid and o-hydroxybenzylamine has been covalently bonded to chloromethylated polystyrene cross-linked with 5% divinylbenzene (abbreviated as PS-H(2)fsal-ohyba, I). Treatment of [VO(acac)2] with PS-H2fsal-ohyba in dimethylformamide (DMF) gave the oxovanadium(iv) complex PS-[VO(fsal-ohyba).DMF] (1). Complex 1 can be oxidized into the dioxovanadium(v) species, PS-K[VO2(fsal-ohyba)] (2) on aerial oxidation in the presence of KOH or into the oxoperoxo species, PS-K[VO(O2)(fsal-ohyba)] (3) in the presence of H2O2 and KOH in DMF suspension. Similarly, PS-[MoO(2)(fsal-ohyba).DMF] (4) has been isolated by the reaction of [MoO2(acac)2] with PS-H2fsal-ohyba. All these complexes have been characterised by various techniques. These complexes catalyse the oxidation of styrene, ethylbenzene and phenol efficiently. Styrene gives five reaction products namely styrene oxide, benzaldehyde, 1-phenylethane-1,2-diol, benzoic acid and phenylacetaldehyde, while ethylbenzene gives benzaldehyde, phenyl acetic acid, styrene and 1-phenylethane-1,2-diol. The oxidation products of phenol are catechol and p-hydroquinone. These catalysts are also able to catalyse the oxidative bromination of salicylaldehyde to 5-bromosalicylaldehyde with ca. 80% selectively in the presence of aqueous 30% H2O2/KBr, a reaction similar to that exhibited by vanadate-dependent haloperoxidases. Their corresponding neat complexes have also been prepared and their catalytic activities have been compared.
TL;DR: In this paper, the thermal degradation of polymethacrylates containing carboxylic groups was investigated by TGA/FTIR, and the analysis of the volatile products from the studied polymers differs notably than those obtained for polymethyl acyclic acid: β-lactones and γ lactones were released from PMBA and PMHA, respectively, during its thermal degradation, whereas an ester derivative from benzoic acid evolves from PMBeA probably through depolymerization.
TL;DR: A chemo- and regioselective copper-catalyzed cross-coupling procedure for amination of 2-bromobenzoic acids is described, which eliminates the need for acid protection and produces N-aryl and N-alkyl anthranilic acid derivatives in up to 99% yield.
Abstract: A chemo- and regioselective copper-catalyzed cross-coupling procedure for amination of 2-bromobenzoic acids is described. The method eliminates the need for acid protection and produces N-aryl and N-alkyl anthranilic acid derivatives in up to 99% yield. N-(1-Pyrene)anthranilic acid has been employed in metal ion-selective fluorosensing. Titration experiments showed that this pyrene-derived amino acid forms an equimolar complex with Hg(II) in water resulting in selective fluorescence quenching even in the presence of other metal ions such as Zn(II) and Cd(II).
TL;DR: The available dermal irritation and sensitization data and ultraviolet (UV) absorption and phototoxicity data demonstrating no adverse reactions to Benzoic Acid support the safety of Benzaldehyde as currently used in cosmetic products.
Abstract: Benzaldehyde is an aromatic aldehyde used in cosmetics as a denaturant, a flavoring agent, and as a fragrance. Currently used in only seven cosmetic products, its highest reported concentration of use was 0.5% in perfumes. Benzaldehyde is a generally regarded as safe (GRAS) food additive in the United States and is accepted as a flavoring substance in the European Union. Because Benzaldehyde rapidly metabolizes to Benzoic Acid in the skin, the available dermal irritation and sensitization data demonstrating no adverse reactions to Benzoic Acid were considered supportive of the safety of Benzaldehyde. Benzaldehyde is absorbed through skin and by the lungs, distributes to all well-perfused organs, but does not accumulate in any specific tissue type. After being metabolized to benzoic acid, conjugates are formed with glycine or glucuronic acid, and excreted in the urine. Little acute toxicity was seen. The oral LD(50) of Benzaldehyde in rats and mice ranged from 800 to 2850 mg/kg. The intraperitoneal LD(50) in white rats was 3265 mg/kg. In short-term oral studies, the no observed adverse effect level (NOAEL) was 400 mg/kg in rats and mice. In subchronic oral studies, the NOAEL was 400 mg/kg in rats and 600 mg/kg in mice. In a 16-week feeding study, rats given up to 10,000 ppm showed no signs of toxicity. Repeated inhalation of volatilized Benzaldehyde produced ocular and nasal irritation at 500 ppm and death in rabbits at 750 ppm. Undiluted Benzaldehyde was irritating to rabbit eyes, causing edema, erythema, and pain. Benzaldehyde was determined not to be a contact sensitizer, but did produce allergic reactions in a maximization test. Clinical reports of allergy to Benzaldehyde are rare. Benzoic Acid did not produce irritation or sensitization reactions in human clinical studies. Benzoic Acid also failed to produce reactions in phototoxicity and photosensitization tests. Neither Benzaldehyde, Benzoic Acid, nor Sodium Benzoate are reproductive or developmental toxicants at doses that are nontoxic to the mother. In a behavioral study, blood levels of 0.12 ng/ml Benzaldehyde produced a 44% reduction in motor activity in mice. Benzaldehyde did not produce mutations in bacterial assays, but did produce chromosomal abnormalities in Chinese hamster cells and increased mutations in a mouse lymphoma forward mutation assay. Benzaldehyde was evaluated by the National Toxicology Program, which found no evidence of carcinogenicity in rats, and some evidence of carcinogenicity in mice. Several studies have suggested that Benzaldehyde can have carcinostatic or antitumor properties. Overall, at the concentrations used in cosmetics, Benzaldehyde was not considered a carcinogenic risk to humans. Although there are limited irritation and sensitization data available for Benzaldehyde, the available dermal irritation and sensitization data and ultraviolet (UV) absorption and phototoxicity data demonstrating no adverse reactions to Benzoic Acid support the safety of Benzaldehyde as currently used in cosmetic products.
TL;DR: Results indicating that SPI1 expression protects the yeast cell from damage caused by weak acids used as food preservatives are consistent with the notion that Spi1p expression upon weak-acid stress leads to cell wall remodeling, especially for the more lipophilic acids, decreasing cell wall porosity.
Abstract: The Saccharomyces cerevisiae SPI1 gene encodes a member of the glycosylphosphatidylinositol-anchored cell wall protein family. In this work we show results indicating that SPI1 expression protects the yeast cell from damage caused by weak acids used as food preservatives. This is documented by a less extended period of adaptation to growth in their presence and by a less inhibited specific growth rate for a parental strain compared with a mutant with SPI1 deleted. Maximal protection exerted by Spi1p against equivalent concentrations of the various weak acids tested was registered for the more lipophilic acids (octanoic acid, followed by benzoic acid) and was minimal for acetic acid. Weak-acid adaptation was found to involve the rapid activation of SPI1 transcription, which is dependent on the presence of the Msn2p transcription factor. Activation of SPI1 transcription upon acetic acid stress also requires Haa1p, whereas this recently described transcription factor has a negligible role in the adaptive response to benzoic acid. The expression of SPI1 was found to play a prominent role in the development of yeast resistance to 1,3-β-glucanase in benzoic acid-stressed cells, while its involvement in acetic acid-induced resistance to the cell wall-lytic enzyme is slighter. The results are consistent with the notion that Spi1p expression upon weak-acid stress leads to cell wall remodeling, especially for the more lipophilic acids, decreasing cell wall porosity. Decreased cell wall porosity, in turn, reduces access to the plasma membrane, reducing membrane damage, intracellular acidification, and viability loss.
TL;DR: A facile headspace solid-phase microextraction (HS-SPME) procedure using 85 microm polyacrylate (PA) fiber is presented for the simultaneous determination of preservatives (sorbic and benzoic acids) in food dressing by gas chromatography (GC) with flame ionization detector (FID).
TL;DR: It has been found that the Schiff base behaves as neutral tridentate (ONO) ligand forming chelates with 1:1 (metal:ligand) stoichiometry.
TL;DR: A novel solid-phase extraction element combined with thermal desorption-gas chromatography (TD-GC) using a pyrolysis-GC system was applied for the determination of the five preservatives in soft drinks, yogurts and sauces, and the linearity of the method was satisfactory over a concentration range.
TL;DR: In this paper, 2.2-pyridylbenzimidazole (2-pybmz) and 3-pymz have been covalently anchored to chloromethylated polystyrene crossed-linked with 5% divinylbenzene in DMF in presence of triethylamine in ethylacetate.
Abstract: 2-(2-pyridyl)benzimidazole (2-pybmz) and 2-(3-pyridyl)benzimidazole (3-pybmz) have been covalently anchored to chloromethylated polystyrene crossed-linked with 5% divinylbenzene in DMF in presence of triethylamine in ethylacetate. These chelating resins readily react with non-isolable metal peroxo species, prepared in situ by stirring V2O5 (in presence of aqueous KOH), MoO3 or WO3 · H2O with an excess of 30% H2O2, to give the corresponding oxodiperoxo complexes, PS-K[VO(O2)2(L)] (L = 2-pybmz: 1, L = 3-pybmz: 4), PS-[MoO(O2)2(L)] (L = 2-pybmz: 2, L = 3-pybmz: 5) and PS-[WO(O2)2(L)] (L = 2-pybmz: 3, L = 3-pybmz: 6). PS-2-pybmz and PS-3-pybmz represent polymer-anchored ligands. Structures of these complexes have been established on the basis of spectroscopic (IR and electronic), thermogravimetric studies and elemental analyses. Oxidation of phenol or styrene with selected catalysts was tested using H2O2 as an oxidant. Oxidation of phenol with ca. 35% conversion gave a mixture of catechol and p-hydroquinone where selectivity towards catechol is ca. 62%. Oxidation of styrene gave five products, styrene epoxide, benzaldehyde, benzoic acid, phenylacetaldehyde and 1-phenylethane-1,2-diol. Various parameters such as amount of oxidant and catalyst, and temperature of the reaction mixture have been taken into consideration for the maximum conversion of substrates. These catalysts are recyclable without considerable loss in their catalytic activities. IR spectral data of both freshly prepared and recovered catalysts are also identical, which indicate that the metal complex moiety is intact during the catalytic reaction.
TL;DR: In this paper, a headspace solid-phase microextraction (HS-SPME) method was developed for the simultaneous determination of sorbic and benzoic acids in beverages, where the analytes were collected from the headspace by using a 65-μm polydimethylsiloxane-divinylbenzene (PDMS-DVB) coated fiber and determined by gas chromatography with flame ionization detector (GC-FID).
TL;DR: To the best knowledge, this is the first demonstration of sensitized emission of luminescent lanthanide complexes based on 4-naphthalen-1-yl-benzoic acid derivatives by the charge-transfer process.
Abstract: The photophysical properties of 4-naphthalen-1-yl-benzoic acid ligands and their Eu(III)-cored complexes were systematically investigated to elucidate the effective energy-transfer pathway in luminescent lanthanide complexes. A series of 4-naphthalen-1-yl-benzoic acid ligands, such as 4-naphthalen-1-yl-benzoic acid (NA-1), 4-[4-(4-methoxyphenyl)-naphthalen-1-yl]-benzoic acid (NA-2), and 4-{4-[4-(4-methoxyphenyl)-naphthalen-1-yl]-benzyloxy}-benzoic acid (NA-3), were synthesized and utilized for the synthesis of their Eu(III)-cored complexes, corresponding to NAC-1, NAC-2, and NAC-3. The fluorescence spectra of NA-1 and NA-2 show large Stokes shifts with increasing solvent polarity. These large Stokes shifts might be dominantly due to the formation of an intramolecular charge transfer (ICT) complex in the excited state. Also, the intensive luminescence of the Eu(III) ions by the photoexcitation of the ligand in NAC-1 and NAC-2 in polar solvents supports that the energy transfer from the ligand to the Eu(III) ion takes place efficiently. In the case of NA-3, which has a -CH2OPh- group that acts as a blocking group, there is no dependence of the fluorescence spectrum on the solvent nature and no luminescence of the Eu(III) ions by the photoexcitation of the ligand, indicating no formation of the ICT state. This can be due to the fact that the formation of the ICT state in NA-3 was prevented because the -OCH2- group acts as a blocking group by interrupting the pi-conjugation between the benzoic acid and the naphthalene unit. From these photophysical studies, we suggest that the ICT state plays a very important role in the energy-transfer pathway from the ligand to the Eu(III) ion. To our best knowledge, this is the first demonstration of sensitized emission of luminescent lanthanide complexes based on 4-naphthalen-1-yl-benzoic acid derivatives by the charge-transfer process.
TL;DR: The porous monolithic columns show high performance at relatively low pressure and the coupling of short monoliths with sequential injection technique (SIA) results in a new approach to implementation of separation step to non-separation low-pressure method.
TL;DR: In this article, four hyperbranched resins having fatty acid residues were synthesized and the physical and mechanical properties of the resins were determined by FTIR spectroscopy and DSC.
TL;DR: In this article, it was shown that the activity of Ru-hydroxyapatite (RuHAp) in the oxidation of benzyl alcohol with molecular oxygen was more than tripled by the incorporation of Ru into organically modified HAp and no detectable product beside benzaldehyde was formed.
TL;DR: The photochemical degradation of BA in the absence of iron (III) occurred at irradiation wavelengths below 300nm and in the presence of Fe(III) was observed at both 254, 350, 419 and under solar irradiation.
TL;DR: Manganese oxides, which are easily prepared, simple to use and capable of being recycled, have been employed as catalyst in the selective oxidation of toluene to benzoic acid for the first time.
Abstract: Manganese oxides, which are easily prepared, simple to use and capable of being recycled, have been employed as catalyst in the selective oxidation of toluene to benzoic acid for the first time. Molecular oxygen was used as oxidant under additive- and solvent-free conditions. As a result, 39% conversion of toluene and 93% selectivity of benzoic acid were achieved.
TL;DR: In this article, a simple and convenient procedure for the reduction of aldehydes and ketones with sodium borohydride activated by solid acids such as boric acid, benzoic acid, and p-toluenesulfonic acid monohydrate under solvent-free conditions is described.